1. Field of the Invention
The present invention relates to a video projector which projects images on an external screen, and especially relates to a video projector having angular adjustability to an installation surface.
2. Description of the Related Art
Conventionally, a video projector, which projects images on an external screen on the basis of image signals outputted from a personal computer, for example, has an angle adjusting mechanism to adjust an angle of an optical axis of a projection lens with respect to an installation surface of the video projector so as to project the image on the screen properly. A conventional angle adjusting mechanism is comprised of a rod-shaped support adjustably provided at a front center of a housing of the video projector, for example, to protrude downward from the bottom of the housing and a locking mechanism to lock the movement of the support. The locking mechanism is further linked with a operation button via a link lever to release the locking of the support by the locking mechanism. The support is locked up by the locking mechanism when it protrudes downward from the bottom of the housing of the video projector, so that the support can hold an inclined posture of the video projector. The support and the locking mechanism has a plurality of hooking points corresponding to protruding height of the support from the bottom of the housing, and thus, the angle of the optical axis of the projection lens with respect to the installation surface can be adjusted. When the operation button is operated by a user, the link lever is moved with the motion of the operation button and it releases the locking of the support by the locking mechanism, so that the support will be retracted inside the housing due to weight of the video projector.
In such angle adjusting mechanism of the video projector, the operation button and the link lever are generally independently formed with different materials. Specifically, the inside of the housing of the video projector becomes high temperature due to heat of a light source and so on, so that an element such as the link lever which is disposed in the vicinity of a heat source or required the rigidity is formed of a metal material or a composite resin material. On the other hand, the operation button which is partially exposed outside is formed of a generic resin material in consideration of a manufacturing cost or an appearance design. Alternatively, if the link lever and the operation button were integrally formed, the shape of the integrated member might have become complex and the manufacturing cost thereof be increased. Thus, the operation button and the link lever, which are independently formed, are coupled with a screw, for example, so that the link lever is moved in conjunction with the motion of the operation button. Since the link lever is a movable member, it is held on the housing with a predetermined allowance in consideration of the dimensional tolerance.
By the way, in such a conventional video projector, when vibrations are applied to the video projector, or sounds are outputted at megavolume from a built-in speaker of the video projector, for example, the link lever is resonated in the allowance. The resonance of the link lever further causes frictional contact of the operation button and edge of a button hole of the housing into which the operation button is inserted, so that frictional sounds are generated due to the frictional contacts of the operation button and the edge of the button hole. Such frictional sounds are rudeness to the user.
In addition, the size of the button hole must be selected a little larger that the size of the outer shape of the operation button in consideration of the dimensional tolerances of the housing, the link lever and the operation button manufactured, so that a clearance between the edges of the button hole and the operation button becomes wider, and thus, visual quality of the video projector is deteriorated. Furthermore, the user may feel the operationality of the operation button is not so good, because the allowance of the operation button to the housing may be felt larger.
Japanese Laid-Open Patent Publication No. 2006-49068 discloses a push knob structure that prevents displacement of a support member and a base member. Although this structure shown in 2006-49068 can prevent the inclination of the push knob, it, however, cannot reduce the frictional sounds due to the frictional contacts of the operation button and the edge of the button hole of the housing, as described above. Furthermore, the visual quality of the video projector cannot be increased, even if the structure is applied to the operation button of the video projector.
Japanese Laid-Open Patent Publication No. 2004-281291 discloses a structure that enables to protrude a operation surface of a push button from a button hole into which the push button is inserted and prevents backlash of a push button, even when a center of the push button is discrepant from a guide of a chassis due to location accuracy of the button hole on a front panel is lower. The structure shown in 2004-281291 cannot increase the visual quality of the apparatus, and the mechanism of the push button becomes complex.